Immobilisation on mesoporous silica and solvent rinsing improve the transesterification abilities of feruloyl esterases from Myceliophthora thermophila

- Four FAEs from M. thermophila C1 were immobilised on mesoporous silica.
- Size-selective immobilisation of proteins was observed.
- Immobilised enzymes were used for transesterification reactions in solvents.
- Enzymes could be reused in nine reaction cycles with less than 10% activity loss.
- Solvent rinsing improved transesterification yield compared to conventional drying.

The immobilisation of four feruloyl esterases (FAEs) (FaeA1, FaeA2, FaeB1, FaeB2) from the thermophilic fungus Myceliophthora thermophila C1 was studied and optimised via physical adsorption onto various mesoporous silica particles with pore diameters varying from 6.6 nm to 10.9 nm. Using crude enzyme preparations, enrichment of immobilised FAEs was observed, depending on pore diameter and protein size. The immobilised enzymes were successfully used for the synthesis of butyl ferulate through transesterification of methyl ferulate with 1-butanol. Although the highest butyl ferulate yields were obtained with free enzyme, the synthesis-to-hydrolysis ratio was higher when using immobilised enzymes. Over 90% of the initial activity was observed in a reusability experiment after nine reaction cycles, each lasting 24 h. Rinsing with solvent to remove water from the immobilised enzymes further improved their activity. This study demonstrates the suitability of immobilised crude enzyme preparations in the development of biocatalysts for esterification reactions.

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